Here is the information for PHP on Windows 8.1.
Updated 12/25/2014
First, you add "Widnows Features" to have IIS get installed. When you open "IIS Manager" using Search, it will prompt you to install "Web Platform Installer" (currently v.5.0 as of 12/25/2014). Install it and run it. When it opens, click Products on the top tabs. Use Search windows to find PHP 5, it will find PHP 5.6.0 (as of 12/25/2014). Double click on it to install. After the installation, you put the following file into web site location as test.php (use IIS Manager and click on Sites on the left pane. Sites shows the actual path for the web site) and test with the url of http://localhost/test.php:
<html> <head> <title>PHP Test</title> </head> <body> <?phpphpinfo();?> </body> </html>